Inspection device

Abstract

The purpose of the present invention is to provide an inspection device that can determine the reliability of an image feature value in a target region of an observation image of a sample. This inspection device extracts a first feature value from a target region including an inspection target in an observation image of a sample, extracts a second feature value from a reference region other than the target region in the observation image, and compares the first feature value and the second feature value, thereby calculating the reliability of the first feature value (see FIG. 1 ).

1 . An inspection device that inspects a sample using an observed image of the sample, comprising:
 a feature extractor that extracts a feature of the observed image; and   a reliability evaluator that evaluates a reliability of the feature,   wherein the feature extractor extracts, within the observed image, a first feature from a target area including an inspection target,   wherein the feature extractor extracts, within the observed image, a second feature from a reference area other than the target area, and   wherein the reliability evaluator compares the first feature with the second feature, thereby calculating the reliability of the first feature.   
     
     
         2 . The inspection device according to  claim 1 ,
 wherein the feature extractor calculates, as the first feature, a first statistical amount of a pixel value of the observed image in the target area,   wherein the feature extractor calculates, as the second feature, a second statistical amount of a pixel value of the observed image in the reference area,   wherein the reliability calculator compares the first statistical amount with the second statistical amount, thereby calculating an evaluation value that represents whether there is a significant difference between the first feature and the second feature, and   wherein the reliability evaluator calculates the reliability using the evaluation value.   
     
     
         3 . The inspection device according to  claim 1 ,
 wherein the reliability evaluator calculates the reliability so that the reliability is higher as a significant difference between the first feature and the second feature is larger.   
     
     
         4 . The inspection device according to  claim 1 , further comprising a reacquisition determiner that determines whether it is necessary to reacquire the observed image after the reliability evaluator evaluates the reliability,
 wherein the reacquisition determiner determines that it is necessary to reacquire the observed image if the reliability is not at or above a reacquisition threshold,   wherein if it is determined that it is necessary to reacquire the observed image, the feature extractor re-extracts a feature of the reacquired observed image, and   wherein if it is determined that it is necessary to reacquire the observed image, the reliability evaluator reevaluates the reliability of the re-extracted feature.   
     
     
         5 . The inspection device according to  claim 4 ,
 wherein even if the reliability is not at or above the reacquisition threshold, the reacquisition determiner determines that it is not necessary to reacquire the observed image if a number of the reacquired observed image is at or above a predetermined value.   
     
     
         6 . The inspection device according to  claim 4 ,
 wherein if a cause of the reliability not being at or above the reacquisition threshold is due to shortage of the observed image at the reference area, the reacquisition determiner determines that it is necessary to reacquire the observed image in the reference area,   wherein if it is determined that it is necessary to reacquire the observed image in the reference area, the feature extractor re-extracts the second feature from the reacquired observed image in the reference area, and   wherein if it is determined that it is necessary to reacquire the observed image in the reference area, the reliability evaluator calculates the reliability by comparing the re-extracted second feature with the first feature.   
     
     
         7 . The inspection device according to  claim 6 ,
 wherein if a cause of the reliability not being at or above the reacquisition threshold is due to shortage of the observed image at the reference area, the reacquisition determiner reacquires the observed image in the target area after reacquiring the observed image in the reference area.   
     
     
         8 . The inspection device according to  claim 1 ,
 wherein the feature extractor extracts, as a derived feature of the observed image, a parameter representing a ratio of pixels of the observed image in the target area that have the feature to an area size of the target area.   
     
     
         9 . The inspection device according to  claim 8 ,
 wherein the reliability evaluator compares the derived feature in the target area with the derived feature in the reference area, thereby calculating the reliability of the first feature.   
     
     
         10 . The inspection device according to  claim 1 , further comprising a target area identifier that identifies the target area from the observed image,
 wherein the target area identifier uses at least one of a brightness value of the observed image or a size of a closed area included in the observed image, thereby determining which part of the observed image is the inspection target and which part of the observed image is not the inspection target, and   wherein the target area identifier identifies, as the target area, an area excluding a portion that is determined as not being the inspection target within the observed image.   
     
     
         11 . The inspection device according to  claim 1 , further comprising a corrector that corrects at least one of the observed image in the target area or the observed image in the reference area. 
     
     
         12 . The inspection device according to  claim 1 , wherein the sample includes at least one of antigen or antibody. 
     
     
         13 . The inspection device according to  claim 12 , wherein the feature extractor extracts, as a feature of the observed image, a number of marker particles adhered to the antigen or to the antibody. 
     
     
         14 . The inspection device according to  claim 1 , wherein the inspection device is configured as a device that acquires the observed image by a charged particle beam. 
     
     
         15 . The inspection device according to  claim 1 , wherein the sample includes at least one of particle, void, base material or liquid.